For the analysis of the structure of a three-dimensional object, a finite element method is mainly used. In the finite element method, a three-dimensional object is expressed by a combination of a plurality of polyhedral elements, and numerical analysis is performed by defining that the respective elements are joined at a finite number of nodes constituting the elements. The operation of dividing a three-dimensional object into a plurality of elements is called mesh division, and a divided mesh of a three-dimensional model to be analyzed is defined by mesh data composed of information about the positions of nodes, etc.
In an electromagnetic field analysis using the finite element method that takes a rotational motion into consideration, a three-dimensional mesh of a rotating machine such as a motor is generated by the following method. In a spatial area between a stator and a rotor, a boundary surface for separating the rotating machine and the spatial area into a stator-side portion and a rotor-side portion is set, and two-dimensional meshes of the stator-side portion and the rotor-side portion are generated on a cross section perpendicular to a rotation axis direction. The generated two-dimensional mesh is extended in the rotation axis direction to generate a three-dimensional mesh of an analysis area composed of the rotating machine and the spatial area. By shifting the three-dimensional mesh of the rotor-side portion from the boundary surface by an amount of one element with respect to the stator-side portion, it is possible to rotate the rotor, and thus it is possible to perform a magnetic field analysis of the rotating machine while rotating the rotor.
Moreover, by generating a three-dimensional mesh of the entire rotating machine including the spatial area every time the rotor is rotated, it is also possible to perform a magnetic field analysis of the rotating machine while rotating the rotor.
With the above-described method of generating a three-dimensional mesh by extending a two-dimensional mesh, it is possible to express the shape of a rotating machine having a simple shape by the generated three-dimensional mesh. However, for a crow-pole type rotating machine or a rotating machine with a coil end having a complicated shape, it is impossible to generate a three-dimensional mesh showing the structure of the rotating machine by extending a two-dimensional mesh since the shape of the rotating machine is not uniform on the cross sections perpendicular to the rotation axis.
On the other hand, with the above-described method of generating a three-dimensional mesh of the entire rotating machine every time the rotor is rotated, it is possible to generate a three-dimensional mesh of a rotating machine having a complicated shape, but it is necessary to regenerate a three-dimensional mesh every time the rotor is rotated, and therefore this method has the problem that it requires enormous calculation time for the analysis.